Distributed playback enables the synchronized presentation and interactive control of ultimedia content by multiple devices over a relatively low-band width network. The bandwidth of the network is considered to be relatively low if it is insufficient for transmitting the entire amount of uncompressed data that shall ultimately be presented at various terminals. While the network bandwidth may well be sufficient for transmitting the multimedia content in a compressed format, it may not be sufficient for transmitting the multimedia content in an uncompressed format such as data in a video interface standard as DVI.
An example use case may be found in automotive industry front and rear-seat entertainment units, where each independently functioning unit is required to simultaneously present the same media content, such as a DVD video disk inserted into a single device. For economical reasons, it is desirable to make use of an existing network infrastructure, rather than dedicated high band width equipment, cables, etc., required for the transmission of audio and video signals to and from each unit, especially when the audio and video signals are provided in a “raw” format.
In the field of infotainment and/or entertainment units, especially for the automotive industry, the distribution of video stream to the various video consumers within the vehicle has seen an increased interest from entertainment unit manufacturers and car manufacturers. Original equipment manufacturers (OEMs) started to ask for separation between the video source and the video consumer(s) due to requirements for flexibility, network transparency and standardization, while avoiding extensive and proprietary wirings.
The research and development challenges imposed on the suppliers are considerable, as the questions to be solved include those regarding a guaranteed bandwidth, low latencies, distributed A/V synchronization, block synchronization and compensation of differing travelling times, as well as a frame-synchronous presentation on several displays.
A system for implementing such a distributed playback architecture is described in PCT/EP 2011/064218, which is incorporated herein by reference.
The distributed playback, however, is not only limited to rear- or front-seat entertainment systems rigidly integrated within car seats or aircraft seats, but a distributed playback is additionally useful in a scenario, in which the rear-seat entertainment devices are mobile devices such as tablet computers which are able to connect to a distributed playback server within, for example, a car or an aircraft. Then, the distribution channel between the distributed playback server and the individual distributed playback clients will not be a local area network cable, but will be a local area network wireless channel.
Additionally, it is to be outlined that the distributed playback architecture does not necessarily have to be implemented in a car, but also can be implemented in any kind of environment (e.g. in a house or room or in-flight, i.e., in a plane or aircraft such as a passenger aircraft), where there is a distributed playback server and where there are one or several distributed playback client devices e.g. located in seats or the car, bus or aircraft, which can communicate with the distributed playback server in order to replay content and/or to exchange commands or user input information etc. A distributed playback architecture has been realized by the company Cinemo, and a Cinemo-enabled client can connect to a Cinemo-enabled server as soon as the communication channel between the client and the server is so that a useful connection between both devices is possible with respect to a certain selected or pre-negotiated communication format.
The disadvantage of this concept is that the connection between the client and the server will always depend on, for example, a wireless communication channel or a wired communication channel. In the case of a wired communication channel, a communication cable between the client device and the server device has to be plugged in, i.e., correctly installed. Irrespective of whether there is a wireless channel or a wired channel, the region of movement away from the server is limited and, on the other hand, there are typical media pieces which need a considerable time to be replayed such as movies or extended playlists. The user may wish to move away from the distributed playback server providing the media content such as the movie, and the user may additionally wish to watch, for example, the end of the movie in a different place where, for example, a connection to the distributed playback server is not possible anymore for certain reasons.